Tubing plug



TUBING PLUG Aug. 3Q, 1932.

4 Sheets-Sheet 1 Original Filed Feb. 26,- 1930 H. C. OTIS TUBING PLUG Aug. 30, 1932.

4 Sheets-Sheet 2 Original Filed Feb. 26, 1950 Q O O O @000 H. C. OTIS TUBING-PLUG Aug. 30, 1932.

Original Filed Feb. 26. 1930 4 Sheets-Sheet 5 $41 1 v I w Aug-80, 1932- H. c.6115 1,874,114

TUBING PLUG Original Filed Feb. 26. 1930 4 Sheets-Sheet 4 fnaeniisri- 3 192%: a 0&5.

y cls glzor'ngs,

- fully disclosed hereinafter,

Serial No. 395,315,

Patented Aug. 30, 1932 STATES PATENT OFFICE Original application filed February 26, 1980, Serial No. 481,510. Divided and this application filed August 19, 1981. Serial No. 558,157.

This application is a division of my application for patent filed February 26, 1930, Serial N 0. 431,510.

This invention is a sequence to the invention disclosed in my co-pending application, filed September 26, 1929.

In the said co-pending application I have described a process and apparatus for inserting tubin in wells in which there exists fluid under hig pressure. The present invention relates to a process and apparatus for removing the tubing from the well under similar conditions.

The process and apparatus forming the subject of the present application will be reference being had to the accompanying drawings, of

' which Figure 1 is a vertical section through a well operating under high pressure and equipped with a string of tubing placed within the well casing in accordance with Fig. 5 is a sectional view showing the tubesealing device in the sealing position adjacent the lower end of the string of tubing;

Fig. 6 is a sectional view showing the next step in the process. with the apparatus by which the tube-sealing element is inserted removed from the upper end of the string of tubing;

Fig. 7 is an elevation, partly in section,

' showing the control heads applied to the upper end of the well casing and the string of tubing being removed through the said control heads;

Fig. 8 is an outside view of the assemblage shown in Fig. 7, with the snubbing gear applied for hoisting the string of tubing out of the well casing during that portion of the tube-removing operation wherein the weight of the tubing exceeds the lifting effect of the pressure in the well; and

Fig. 9 is a view somewhat similar to Fig. 8, but showing the snubbing gear arranged for holding the tubing against the pressure in the well after such an amount of the tubing has been removed as would reduce the weight of the string of tubing to a point below the lifting effect of the pressure in the well. I

As shown in Fig. 1 of the drawings, the operating well is equipped with the usual casing 1, which consists of a plurality of lengths of ordinary piping coupled together by ordinary straight couplings (not shown). A gate valve 5 is mounted on the upper end of the well casing 1 in place of one of the said straight couplings for purposes hereinafter set forth.

Threaded into the upper end of the coupling or gate valve 5, as the case may be, is a nipple 6, which is provided with an annular shoulder 7 formed on its inner surface, for purposes hereinafter set forth.

The string of tubing 2, which is located within the well casing 1, consists primarily of a plurality of lengths of ordinary pipe of lesser diameter than the well casing 1. These pipe sections are connected-together in the usual manner by straight couplings 10.

In some wells which have been equipped with a string of tubing the lowermost section of the string of tubing is perforated and rests directlyon the bottom of the well. In the present instance I have shown the string of tubing 2 as being provided with a foot plug 11 secured in one end of one of the couplings 10, and adapted to rest on the bottom of the well, a section of tubing of any desired length being threaded into the upper end of the lowerinost coupling 10 with its opposite end threaded into the lower end of a second coupling 10. In the upper end of the second coupling 10 is threaded a perforated screen section 12.

In the present instance the upper end of the screen section 12 forms the inner memher 45 of a telescoping device 13, which as set forth in the said co-pending application, was used as a supporting and breaking device for a temporary seal by which the fluid pressure is prevented from passing through the string of tubing 2 while the same was being lowered into the well casing 1. The telescoping element 13 also comprises an outer section 40 having slots 48 formed therein into which project lugs 47 which extend laterally from the inner section 45 of the telescoping device 13. By this means the sections 40 and 45 of the telescoping device 13 are operatively connected.

The upper end of the outer section 40 of the telescoping device 13 is adapted to receive the threaded end of one of the pipe sections of which this string of tubing 2 is composed and, during the inserting process described in the above mentioned co-pending application, a sealing disc is normally disposed between the lower end of the one section of tubing and an annular shoulder or rib 41 formed on the inner surface of the outer section 45 of the telescoping device 13. The two sections 40 and 45 of the telescoping device 13 are adapted for longitudinal movement with respect to each other, by which the above mentioned sealing disc is broken by a knife blade or other protuberance 50 carried by the inner section 45 of the said telescoping device, whereafter the annular rib 41 of the said outer section rests on the upper end of the inner section 45, thereby supporting that portion of the tubing lying above the telescoping device 13.

The escape of pressure from the well casing 1 around the outside of the string of 'tub ing 2 is normally prevented by a series of packing elements 56, 57 and 58, the element 56 resting on the annular shoulder 7 of the nipple 6 whichis carried by the upper end a of the well casing 1 as above noted. The element 57 is adapted to receive and engage the lower end of one of the tubing couplings, as indicated at 10?). The packing elements 56 and 57 are usually composed of metal, while the packing elements 58, interposed between the elements 56 and 57, are composed of a resilient material which will spread lateral- 1y when compressed longitudinally and thereby form a seal between the inner surface of the portion of the nipple 6 lying above the shoulder 7 and the outer surface of the string of tubing 2.

Above the coupling 10?) is another set of sealing rings indicated at 60. 61. 62, the rings 60 being adapted to engage the upper end of the coupling 10?) while the ring 61 is adapted to be engaged by an inturnedv flange 66 formed on a cap element 65. which is threaded onto the nipple 6 and adapted to compress the packing elements 58 and 62 longitudinally to form the seal as above noted.

Threaded into the coupling 10b is a relatively short section of tubing 21;, on the upper end of which is mounted a gate valve 70, by which the flow of fluid through the string of tubing 2 is normally controlled.

Threaded into the opposite end of the gate valve 70. is a short nipple 71 on which is mounted a T-fitting 72, a second short nipple 73 being threaded into the opposite end of the T-fitting 72, in alignment with the nipple 71 and being provided on its upper end with a second gate valve 75, the upper end of which is provided with a threaded plug 76, for purposes fully disclosed in the above mentioned co-pending application. Threaded into the laterally extending boss of the T-fitting 72 is a service pipe 65 in which is mounted a gate valve 86.

The above description is that of a well which is in normal operation, fluid passing up through the string of tubing 2 and into the service pipe 85 under the control of the gate valves and 86, the gate valve being normally closed when the well is in operation.

In order to remove the string of tubing from the well which is operating under high pressure, it is necessary to first stop the fluid from passing into and through the string of tubing, and for reasons which will be apparent hereinafter the'sealing of the string of tubing must be effected as close as possible to the lower end of the string of tubing and above the perforated or screen section thereof.

It is also necessary to prevent the escape of fluid under pressure through the well casing 1 around the outside of the string of tubing 2 while the tubing is being removed from the casing.

For the purpose of sealing the string of tubing, adjacent the lower end thereof, I provide a sealing unit 100 shown in Figs. 2 to 7 inclusive. The tube-sealing device 100 comprises a hollow cylindrical core member 101 having an annular flange 102 disposed intermediate its ends. Below the flange 102 and surrounding the core element 101 is a packing element consisting of a resilient sleeve 103, which, in the present instance, is composed of rubber.

Disposed around the cylindrical core member 101, above the flange 102, is a frusto-conical sleeve 104, and mounted on the outside of frusto-conical sleeve 104 is a plurality of shoes, two of which are shown at 107 and 108. The shoes are provided with serrated surfaces 106 for purposes hereinafter set forth. The frusto-conical sleeve 104 is provided with longitudinally extending key members or ridges 109 adapted respectively to fit in grooves 110 formed in and extending longitudinally of each of the shoes 107. 108, whereby the separate shoe elements 107 and 108 are respectively guided longitudinally of the sleeve 104.

Obviously any desired number of shoes may be used or, if desired, the shoes may be formed as a complete sleeve 105 surrounding the frusto-conical sleeve 104 and split longiv tudinally to provide two, or more, separate shoe elements.

Disposed above the upper end of the sleeve 104 is an abutment ring 111 which holds the sleeve 104 down against the annular flange or rib 102 of the core member 101, the abutment ring 111 being locked in place by a locking nut 112 threaded onto the upper portion 113 of the core member 101.

Extending longitudinally through the hollow cylindrical core member 101 is a rod 115, on the lower end of which is mounted a frustoconical plug valve element 116 which is adapted to engage a beveled seat 117 formed in the mouth of the lower portion 118 of the hollow core member 101.

Threaded onto the rod 115, below the plug 116, is a nut element 119 into which is threaded. a rod,'or pipe section, 120. On the upper end of the rod 115 is formed a head 121 having laterally extending lugs or ears 122 which are adapted normally to rest on the upper end 113 of the core member 101. Spaced below the ears 122 the said head 121 is provided with shoulders 123 for purposes hereinafter set forth.

The head 121 is provided with an aperture 124 adapted to receive a laterally extending rojection 126 of a supporting element 125.

he supporting element 125 is adapted to lie within the upper end 113 of the core member 101, between one side of the head 121 and the adjacent inner surface of the core member 101 a resilient member in the form of a flat sprlng 127 being carried by the head 121 and adapted to engage the opposite side of the inner surface of the hollow core member 101, whereby the supporting element 125 is held in contact with the opposite side of the said core member 101 for the purpose of retaining the lug 126 of the supporting element 125 within the aperture 124 formed in the head 121.

For the purpose of facilitating the removal of the supporting element 125 from the head 121, the upper side 128 of the lug 126 is inclined as illustrated clearly in Fig. 5. The corresponding side of the aperture 124, .with which the side 128 engages, may be correspondingly inclined if desired.

The upper end of the supporting element- 125 is apertured as illustrated at 129 for the reception of a suspending wire or cable 130, by which the sealing element 100 is adapted to be lowered into and'through the string of tubing 2 and subsequently operated to effect the sealing of the tubing 2.

In order to permit the sealing unit 100 to be lowered through the string of tubing 2 the short nipple 71 is removed from the up-' per end of the gate valve 70, which has previously been closed to stop the flow of fluid through the string of tubing into the said nipple 71. Obviously, all pi fittings and ot er equipment disposed a ove the gate valve are removed with the nipple 71.

Into the u per end ofthe gate valve 70, from which tlie nipple 71 has been removed, is threaded a substitute pipe section 131, within which the sealing element 100 has previously been inserted, with the control wire 130 passing through any desired form of sealing device, which in the present instance shows the wire 130 as passing through an opening 132 formed in the center of a cap 133 which is threaded onto the upper end of the pipe section 131. The cap 133 is provided with an annular cavity 134 having a tapered wall 135, between which an a correspondngly formed wall 136, of an annular cavity 13 formed in an auxiliary cap 138, is disposed, packing 139, which encircles the control wire 130 and prevents the escape of fluid around said suspending wire 130.. As shown in the drawings the auxiliary cap 138 is threaded onto the cap 133 for the purpose of compressing the packing element 139 therebetween.

After the substitute pipe section 131 has been positioned on the valve 70, in the manner illustrated in Figs. 2 and 3, the said valve is opened, thereby permitting the passage of the sealing element 100 through the valve and into the string of tubing 2, as the control wire 130 is fed through the cap 133-138, disposed at the upper end of the pipe section 131. v I

As the sealing unit 100 passes down through the string of tubing the fluid in the string of tubing, displaced by the sealing unit 100, passes through the center opening 140 of the said unit, thereby permitting the unit to settle downwardly through the tubing with the valve plug 116 hanging below the valve seat 117, as shown in Figs. 3 and 4. The said sealing element 100 passes down through the string of tubing until the stop rod 120 engages the disc breaker 50 located at the upper end of the telescoping section 13 of the string of tubing.

In wells where the telescoping unit 13 for breaking the temporary seal has not been used the stop rod 120 is of such a length that it engages the bottom of the well, just prior to the positioning of the sealing unit 100 above the upper end of the screen section of the string of tubing.

In either case the engagement of the stop rod 120 with a fixed abutment in the string of tubing causes the valve plug 116 to be stopped in its downward movement, after which the sealing element 100 will move to a some extent relative to the valve plug 116 or until the seat 117 at the lower end of the central core member engages with the valve plug 116.

In order to positively seat the valve plug 116 on its seat 117 the control wire 130 is I pulled upwardly. The shoes 107 and 108,

of the sleeve 105 have moved downwardly on and relative to the frusto-conical sleeve 104 until the teeth 106 of the said shoes engage the inner surface of the string of tubing 2 and when the wire 130 is pulled upwardly the teeth 106 bite into the tubing 2 and prevent upward movement of the core member 101.

Continued pulling of the wire 130 draws the rod 115 vertically through the said core member 101, positively seating the valve plug 116 on its seat 117, thereby stopping the flow of pressure through the core member 101. When the upper end of the string of tubing is subsequently opened to the atmosphere; the fluid pressure in the lower part of the string of tubing reacts against the lower surface 141 of the rubber packing element 103 tending to move this element upwardly. The pressure exerted against the under side 141 of the packing element 103, the upper end of which is at that time abutting the now rigidly disposed flange 102 of the core member 101, causes a lateral expansion of the said packing element, caused by the longitudinal contraction thereof, due to the pressure exerted on its lower side 141, as clearly shown in Fig. 5.

The longitudinal movement of the rod 115 relative to the core member 101 raises the shoulders 123 of the head 121 formed on said rod to a point immediately above the upper end 113 of the core member 101 whereupon the spring 127 flexes the rod 115 from the position' shown in Fig. 4 to that shown in Fig. 5, the head 121 being moved from the position wherein the shoulders 123 lie substantially across the center of the core member 101, which is the point of greatest dimension of the said core member, to a point at one side of the center, wherein the shoulders 123 assume a position on a shorter cord of the are described by the inner surface of the core member 101, thereby bringing the shoulders 123 into a position where they will contact with the upper end 113 of the core member, at the opposite ends of the said shorter cord.

At the same time the lower edge 142 of the supporting member 125 is raised above the upper end of the core member 101, and, due to the angularity of the upper surface 128 of the pro ection 126 on the supporting member 125, continued movement upwardly of the wire 130 releases the lug 126 from the aperture 124 at the upper end of the rod 115, leaving the unit 100 in sealing position in the lower end of the string of tubing 2, and above the screen section thereof.

While the setting of the sealing unit 100 has been described as beingefi'ected by the stop rod 120 engaging a fixed abutment in the string of tubing or by engaging the bottom of the well, the sealing unit may be set at any desired level in the string of tubing without the aid or use of the stop rod 120. This may pending wire or cable 130, with the sealing unit 100 attached to the one end thereof, into the substitute pipe section 131, through the packing gland 139 at the top end thereof, it being noted that the well pressure at such time completely fills the tubing up to the cap 133. \Vhen the measured amount of the suspending wire 130 has been fed through the cap 133 the string of tubing 2 may then be opened to the atmosphere at any desired point above the sealing element 100 in its assumed position. This may be accomplished by removing the packing gland 138139, or by removing the whole of the cap 133, or by providing a bleeding valve in the substitute pipe 131. In any event as soon as the pressure above the sealing element 100 is reduced a pressure differential is set up in the tubing and the pressure below the sealing unit 100 being the greater tends to raise the sealing unit 100 in the tubing, whereupon the shoes 107 and 108 will grip the tubing wall and prevent such upward movement of the sealing unit 100, as a unit. Continued flow of the well pressure from below the sealing unit 100 will then exert energy upon the lower end of the rubber packing sleeve 103, compressing it longitudinally and thereby causing it to expand radially into sealing contact with the tubing wall. 1

The well pressure will then become effective against the valve 116 causing it to rise and become seated against the valve seat 117 at the lower end of the core tube 101 and at the same time raising the rod 115 until the head 121 thereof is above the upper end of the core tube 101, which releases the hook 125 in the .manner above noted. The wire or cable 130 may then be removed from the tubing, as noted above, leaving the sealing unit 100 effective at the level in the string of tubing 2 as determined by the length of wire or cable 130 fed into the string of tubing before the pressure above the sealing unit was exhausted.

The wire 130 is then Withdrawn until the supporting element 125 lies within the substitute tube section 131, whereupon the substitute tube section 131 and the valve 7 0 are removed from the upper end of the tube sec tion 26. The cap and the packing elements 60, 61 and 62 are then removed from the tube section 27), after which the said tube section 2?) is removed from the coupling 10?), leaving only those elements in and on the well casing as are shown in Fig. 6.-

The weight of that portion of thestring of tubing, being supported by the uppermost coupling 10?), still retains the packing elements 58, disposed between the lower end of the coupling 10?) and the shoulder 7 of the v the control head 3 to the upper threaded end nip 'le 6, in sealing contact with the inner surace of the said nipple and the outer surfee; of the string of tu ing 2, as clearly shown in ig. 6.

The next step in the operation is to apply of the nipple 6, a short nip 1e 8- being threaded into the upper'end 0 the control head 3 and adapted to receive the lower end of the second controlhead 4. The fitting 9 is then threaded into the upper end of the control head 4, and the stationary snubbing device 30 may at this time, or later, be secured to the upper end of the fitting 9, in the manner shown in Fig. 7.

The snugging device 30, as shown and described in the said co-pending application, comprises a substantially fixed tooth shoe 32 adapted to be moved longitudinally of the cross-head 30, by means of a control screw 35. The shoe 32 is adapted to engage one side of the string of tubing while a second toothed shoe 33 is adapted to engage'the opposite side of the string of tubing, as will be hereinafter described. Ihe shoe 33 is pivoted to one end of a lever 34, which in turn is pivotally mounted in the cross-head 30.

A suitable length of tube 20 is then passed down through the snubbing device 30, if this device has already been applied to the fitting 9, the tube section 20 then passing through the fitting 9, the control head 4, the nipple 8 and the control head 3 and threaded into the coupling 10?; from which the tube section 2?) has been removed, it being understood that if the snubbing device 30 has been applied the snubbing jaws 32 and 33 thereof are spread apart to permit thepassage of the tube section 20, and the movable jaws or pistons of the control heads 3 and 4 are like wise opened to permit the tree passage of the said tube section. The jaws 15, 15 of the upper control head 4 are then closed as illustrated in Fig. 7 into sealing contact with the outside of the section of the string of tubing 2 and the toothed jaw 32 of the snubbing device will rest in contact with the outer surface of the tube section 20 as clearly shown in Fig. 7.

For the purpose of extracting the string of tubing from the well casing, I prefer to use one of the many well known contrivances provided for the purpose, which are generally referred to in the oil fields as blocks and elevators. Such a device I use until so much of the string of tubing has been removed from the well casing that the weight of the portion of thestring of tubing remaining within the well casing will no longer overbalance the gas pressure in the well casing, the gas pressure will then tend to blow the tubing out of the well casing.

For the purpose of illustrating one way in which the string of tubing could be extracted from the well casing, I have shown the movable snubbing device 26 as being applied to the section 20 of the strii ig of tublng 2, as

clearl shown in Fig. 8. e movable snubbing evice 26 comprises a carrier, in the opposite ends of which are ivotally mounted a fpair of levers 24, 24, an on the inner ends 0 the levers 24, 24 are pivot-ally mounted toothed snubbin shoes 28, 28 respectively. To the outer en s of the levers 24, 24 is secured the opposite ends of a cable 23, which )ass upwardly and around a movable hoisting block 27 The movable snubbing device 26 is adapted to be moved downwardl on the section of tubing 20 to a position directly above the stationary snubbing device 30, a suitable handle 150 being applied to the lever 34 of the stationary snubbin device 30, after which the movable block 2 may be raised, to cause the toothed shoes 28, 28 of the movable snubbing device 26 to grip the opposite sides of the section 20 of the string of tubing 2, and as the I block 27 is raised the string of tubing 2 is correspondingly hoisted until the coupling 10?) has passed through the control head 3 and is disposed between the two control heads 3 and 4 respectivel The string of tu ing may then be held, or snubbed against downward movement, by raising the outer end of the lever handle 150, which moves the toothed shoe 33 into contact with the string of tubing, pressing the same into gripping contact with the relatively fixed shoe 32 of the fixed snubbing device 30.

The coupling 10?) of the string of tubing having passed above the jaws 15 of the lower control head 3, these jaws are closed into sealing contact with the outer surface of the string of tubing 2 and the jaws 15 of the upper control head 4 are opened to permit the pasage of the coupling 106 through the control head 4.

While the string of tubin is being held against downward movement %y the snubbing jaws 32 and 33, the movable snubber 26 may then be lowered to av point adjacent the stationary snubbing device 30, to obtain a new grip on the string of tubing. Subsequent upward movement of the block 27 again raises the string of tubing 2, and the operations above noted may be repeated as each of the couplings 10 of the string of tubing approaches the jaws 15 of the control heads 3 and 4, it being noted that at no time will the jaws of the control head 3 and those of the control head 4 be opened simultaneously. While the jaws of one are opened to permit the passage of a coupling therethrough, the jaws of the other control head are closed to prevent the escape of fluid pressure around the outside of the string of tubing 2.

As the coupling 10 next below the coupling 10?) on the string of tubing 2 passes up into the nipple 6, the upper end of the coupling engages the lower packing element 56 which up to the present time has been seated on the annular shoulder 7 of the nipple 6, and as the string of tubing is raised the acking elements 56, 57 and 58 are moved out o the nipple 6 and carried on through the control heads 3 and 4, and the movable jaws 32 and 33 of the stationary snubbing device 30, it being noted that the jaws 15 and 32, 33 may be moved far enough apart to permit the passage of the said packing elements 56, 57 and 58.

The hoisting of the string of tubing continues in intermittent steps, regardless of the means employed for accomplishing the result, until sufiicient of the string of tubing 2 has been removed to reduce the total weight of the portion of the string of tubing remainingin the casing 1 to a point below the pressure exerted on the lower end of the tubing by the fluid in the well casing 1, after which the said remaining portion of the string of tubing, if not controlled, would be blown out of the casing 1 by the said pressure therein.

In order to control the movement of the remaining portion of the string of tubing as it moved out of the well casing the stationary snubbing device 30, if not previously applied because of the use of the well known elevators, is now secured in place on the fitting 9, or if already in place as having been used in connection with the movable snubber 26 for raising the tubing, its position is reversed from that shown in Fig. 8 to that shown in Fig. 9, and the movable snubbing device 26 is placed in similar inverted order on the portion of the tubing which extends above the stationary snubber 30 in such a manner that the jaws 28 thereof will grip the tubing when the cable I 23 becomes taut.

A cross arm 20 is then secured to the fitting 9 by bolts 21, 21 and the cable 23 is passed downwardly and around sheaves 22, 22 which are rotatably mounted in the opposite ends of the cross-arm 20, the cables 23 then passing upwardly to themovable block 27 as clearly shown in Fig. 9.

The remaining portion of the string of tubing 2 is then removed by an intermittent retarding action, rather than by the hoisting action previously described, the pressure in the well casing 1 acting as the means for raising the tubing with respect to the casing 1, the retarding action being effected by lowering the movable snubbing device 26 to a point adjacent the stationary snubbing device 30, while the tubing is being held against vertical movement by pressure exerted downwardly on the outer end of the handle 150, the movable block 27 being raised to its highest position at this time. 4

When the holding force is reduced on the handle the pressure within the casing 1 forces the tubing 2 out of the said casing and the said string of tubing 2 is gripped by the movable snubber 26, after which the movement of the string of tubing 2 out of the casing 1 is controlled by lowering the movable block 27 which pays out the cable 23 and permits the tubing 2 to move upwardly out of the casing, under the control of the movable snubber 26 by which the tubing 2 is held at this time.

In order to obtain a new purchase on the tubing 2 pressure is again applied to the handle 150 which stops the outward movement of the string of tubing and the string of tubing is held by and between the toothed jaws 32 and 33 of the stationary snubbing device 30 while the movable snubbing device 26 is moved downwardly along the string of tubing to a new position adjacent the stationary snubbing device 30 the block 27, being raised accordingly. These operations are repeated until the entire string of tubing 2 has been removed from the well casing 1, or until such time as the lowermost section 2d of the string of tubing is brought into position to be gripped by the jaws 15 of either one or'the other or both of the control heads 3 and 4, after which the portion of the string place, the said outer section 40 during the 3 tube-removing operation having been raised and turned with respect to the inner section 45 thereof, until the lugs 47 rest under the shoulders 49 of the slots 48 in which the said lugs 47 are positioned, whereafter the new string of tubing may be inserted by the process disclosed in my said co-pending application.

If the entire string of tubing is to be removed, such as may be required in order to make repairs thereto, or for the purpose of inserting a string of tubing having a larger diameter than that removed, or for inserting a drill stem or other tool into the well casing, the well casing is sealed by closing the gate valve 5 after the lowermost portion of the string of tubing has passed therethrough, and while the gas and oil are still prevented from escaping around the tubing by the sealing elements 15, 15 of the control heads 3 and 4. The necessity for this will be apparent, for the reason that when the string of tubing is entirely removed the gas and oil would flow through the opening formed by the grooves in the pistons 15, through which the tubing,-etc. ordinarily passes.

The valve 5 remains closed while pistons 15 having grooves which will form an opening corresponding to the diameter of the new string of tubing, etc., which is to be inserted into the well casing, are being installed in control heads 3 and 4.

From the above, it will be obvious that I can efficiently remove one string of'tubing from a well in which there exists fluids under high presure and insert a string of'tubing of smaller diameter, when required by a decrease in the flow of the well, without loss of gas or oil, and at the same time eliminate the dangers to the workmen and apparatus, ,which prior to my invention have made the inserting and removing of tubing in high pressure wells or the changing oftubing in such wells practically impossible.

I claim:

1. A tube-sealing unit comprising a hollow core member, a packer surrounding the core member for providing a seal between the tube and the core member, a Valve for closing the hollow core member at one end thereof, a rod supporting the valve and assing through the core member to the opposite end thereof, and a shoulder on the rod adjacent the last said end of the core member and arranged to be hooked onto the said adjacent end of the core member for securing the valve in closing relation to the first said end of the core member.

2. A tube-sealing unit comprising a hollow core member, a packer surrounding the core member for providing a seal between the tube and the core member, a valve for closing the hollow core member at one end thereof, a rod supporting the valve and passing through the core member to the opposite end thereof, a head on the rod adjacent and normally disposed within the last said end of the hollow core member for maintaining the rod in pre determined position in the hollow of the core member, and a shoulder on said rod arranged to be hooked onto the last said end of the core member for securing the valve in closing relation to the first said end of the core member.

3. A tube-sealing unit comprising a hollow core member, a packer surrounding the core member for providing a seal between the tube and the core member, a valve for closing the hollow core member at one end thereof, a rod supporting the valve and passing through the core member to the opposite end thereof, a head on the rod adjacent and normally disposed within the last said end of the hollow core member for maintaining the rod in predetermined position in the hollow of the core member, a readily detachable hook for moving the rod and valve longitudinally of the core member and normally held in operative engagement thereto by contact with the wall of the hollow core member, and a shoulder on said rod arranged to be hooked onto the last said end of the core member upon said longitudinal movement of the rod for securing the valve in closing relation to the first said end of the core member.

4. A tube-sealing unit comprising a hollow core member, a packer surrounding the core ing the rod and valve longitudinally of the 1 core member and normally held in operative of the hollow core member, a shoulder on said rod arranged to be hooked onto the last said end of the core member upon said longitudinal movement of the rod for securing the valve in closing relation to the first said end of the core member, and means for swinging the last said end of the rod laterally into said valve-retaining position upon said longitudinal movement of the rod.

5. A tube-sealing unit comprising a hollow core member, a packer surrounding the core member for providing a seal between the tube and the core member, a valvefor clos ing the hollow core member at one end thereof, a rod supporting the valve and passing through the core member to the opposite end thereof, a head on the rod adjacent and nor mally disposed within the last said end of the hollow core member for maintaining the rod in predetermined position in the hollow of the core member, a valve-setting member within the said hollow of the core member between the head and the wall of the hollow core member, a hook on said valve setting member entering an opening in said head, and resilient means between the head and the opposite side of the core member for maintaining the hook and head in operative relation to each other.

6. A tube-sealing unit comprising a hollow core member, a packer surrounding the core member for providing a seal between the tube and the core member, a valve for closing the hollow core member at one end. thereof, a rod supporting the valve and passing through the core member to the opposite end thereof, a head on the rod adjacent and normally disposed within the last said end of the hollow core member for maintaining the rod in predetermined position in the hollow of the core member, a valve-setting member within the said hollow of the core member between the head and the wall of the hollow core member, a hook on said valve setting member entering an opening in said head, and a spring carried by the head and engaging the opposite side of the hollow of the core member for holding thekhead in operative engagement with the hoo 7. A tube-sealing unit comprising a hollow core member, a packer surrounding the core member for providing a seal'between the tube engagement thereto by contact with the wall and the core member, a valve for closing the hollow core member at one end thereof, a rod supporting the valve and passing through the core member to the opposite end thereof, a head on the rod adjacent and normally disposed within the last said end of the hollow core member for maintaining the rod in predetermined position in the hollow of the core member, a valve-setting member within the said hollow of the core member between the head and the wall of the hollow core member, a hook on said valve setting member entering an opening in said head, a spring carried bythe head and engaging the opposite side of the hollow of the core member for holding the head in operative engagement with the hook, and a shoulder on the head arranged to hook over the end of the hollow core member for holding the valve in closing position with respect to the first said end of the core member upon said longitudinal movement of the rod.

8. A tube-sealing unit comprising a hollow core member, a packer surrounding the core member for providing a seal between the tube and the core member, a valve for closing the hollow core member at one end there- 'of, a rod supporting the valve and passing through the core member to the opposite end thereof, a head on the rod adjacent and normally disposed within the last said end of the hollow core member for maintaining the rod in predetermined position in the hollow of the core member, a valve-setting member within the said hollow of the core member between the head and the wall of the hollow core member, a hook on said valve setting member entering an opening in said head, the cooperating engaging surfaces of the hook and opening in the head being arranged at obtuse angles to the longitudinal center line of the rod for readily disengaging the hook from the head upon predetermined movement of the valve-seating member in a direction longitudinally of the rod.

HERBERT C. OTIS. 

